QUALITY ASSESSMENT OF EUROPEAN ASH FRAXINUS EXCELSIOR L. GENETIC RESOURCE FORESTS IN LATVIA

In Latvia, two European ash (Fraxinus excelsior) genetic resource forests (GRF) have been designated in Skriveri and Bervircava. However, as the degree of damage of ash by the pathogenic fungus Hymenoscyphus fraxineus has increased, many stands have died and many do not comply anymore with minimum requirements for GRF. The aim of the present research was to evaluate and examine the quality of ash GRFs. In each forest unit, one 20x20 m plot was established, and the first (E3) and second (E2) layer projective cover of each species was determined in August 2014. All undergrowth and advance regeneration species were counted and the degree of ash damage by H. fraxineus was determined along a diagonal 25x1 m transect in each plot. In total, 101 plots were established. Quality evaluation was carried out according to the basic criteria for selection of GRF as well as based on criteria cited in other research. Their variation was established by using principal component analysis. Ash in layer E3 was better maintained in Skriveri, but ash regeneration there was worse, as well as a higher degree of damage by H. fraxineus was observed. Ash regeneration density is significantly influenced by its cover on layers E3 and E2 as well as by tree species dominating the growth. The most valuable GRFs have been maintained in Skriveri where 50% of units were rated of average quality and few of bad quality. In Bervircava, 56% of forest units were of bad and very bad quality.